A Review on Vibration Control of Multiple Cylinders Subjected to Flow-Induced Vibrations

The fatigue damage caused by flow-induced vibration (FIV) is one of the major concerns for multiple cylindrical structures in many engineering applications. The FIV suppression is of great importance for the security of many cylindrical structures. Many active and passive control methods have been employed for the vibration suppression of an isolated cylinder undergoing vortex-induced vibrations (VIV). The FIV suppression methods are mainly extended to the multiple cylinders from the vibration control of the isolated cylinder. Due to the mutual interference between the multiple cylinders, the FIV mechanism is more complex than the VIV mechanism, which makes a great challenge for the FIV suppression. Some efforts have been devoted to vibration suppression of multiple cylinder systems undergoing FIV over the past two decades. The control methods, such as helical strakes, splitter plates, control rods and flexible sheets, are not always effective, depending on many influence factors, such as the spacing ratio, the arrangement geometrical shape, the flow velocity and the parameters of the vibration control devices. The FIV response, hydrodynamic features and wake patterns of the multiple cylinders equipped with vibration control devices are reviewed and summarized. The FIV suppression efficiency of the vibration control methods are analyzed and compared considering different influence factors. Further research on the FIV suppression of multiple cylinders is suggested to provide insight for the development of FIV control methods and promote engineering applications of FIV control methods

柱体流激振动能量俘获理论与技术研究若干进展

潮流能分布广泛，且储量巨大，具备巨大的规模化开发利用价值。流激振动是一种常见的流固耦合现象，通过柱体流激振动能够在流速较低时实现有效的能量转换，基于柱体流激振动的能量俘获技术在未来具备广阔的工程应用前景。近年来，针对柱体结构流激振动特性和能量俘获性能，出现了大量的实验和数值仿真研究工作。本文全面阐述了多种截面形式的单个柱体、柱群结构流激振动能量俘获理论与技术方面的研究进展：对于单个圆柱流激振动能量俘获，目前已基本揭示了被动湍流控制器参数、系统阻尼、雷诺数、边界条件等因素对能量俘获性能的影响规律,基本完成了理论和技术积累；对于非圆截面柱体流激振动能量俘获，已初步明确特定来流攻角、系统质量比、系统阻尼、系统刚度、雷诺数条件下三角形、四边形、多边形、异形等多种截面形式柱体的流激振动作用机理和能量俘获能力；对于柱群的流激振动能量俘获，各柱体振子之间存在流场干涉，需要合理设计柱体排布形式、柱体间距、系统阻尼等参数，实现流体能量俘获最大化。通过综述国内外流激振动能量俘获理论和技术方面的研究进展，对今后该问题的研究进行了力所能及的展望，期望促进流激振动能量俘获理论的发展和流激振动能量转换装置的工程应用

复杂海洋环境下管道结构的涡激振动控制研究

复杂海洋环境下海洋管道的涡激振动控制一直面临效果不稳定的问题。通过系列的海洋管道涡激振动模型试验,研究了复杂海洋环境下常用涡激振动抑制装置螺旋列板、控制杆的振动抑制效果,分析了抑制装置的工程适用条件。研究表明:在斜向流条件下,螺旋列板的抑制效果随斜向流角增大而减弱,而控制杆的抑制效果受斜向流角的影响较小;在时变轴向力作用下,螺旋列板的抑制效果受轴向力激励幅值比影响显著,幅值比超过0.1后抑制效率显著下降;在尾流干涉作用下,螺旋列板对上游立管的抑制效果仍然较好,但对下游立管的抑制效果显著变差,甚至有可能增强振动

时变轴向力作用下柔性圆柱涡激振动及抑制研究

海洋立管、TLP平台张力腿、水中悬浮隧道系缆等柔性圆柱结构易受多种因素的影响发生疲劳损伤。海流诱发的涡激振动是海洋工程柔性圆柱结构长期面临的威胁。柔性圆柱结构的轴向力发生周期性变化时,会诱发结构的参激振动。涡激振动与参激振动相互耦合,使柔性圆柱的振动特性更为复杂,也为振动抑制增添挑战。为了研究柔性圆柱结构涡激-参激振动特性及振动抑制问题,设计了变轴向力柔性圆柱涡激振动试验系统,开展了时变轴向力作用下柔性圆柱涡激振动及抑制模型试验。通过分析振动位移、响应频率、运动轨迹等,揭示时变轴向力对柔性圆柱涡激振动特性和振动抑制效果的影响。涡激-参激耦合振动的幅值显著增大,随着时变轴向力幅值比的增大,时变轴向力对涡激振动的影响增强,螺旋列板对涡激-参激耦合振动的抑制效果减弱

流固耦合力学专题序

流固耦合力学是流体力学与固体力学交叉而成的力学分支,以两相介质之间的相互作用为重要特征,研究可变形固体在流场作用下的行为及固体变形对流场影响的相互作用.流固耦合现象存在于海洋工程、航空航天、石油化工、核能工程、土木工程等几乎所有涉及国计民生的重大领域中,并会诱发结构静发散

Dynamic response characteristics of pier-type submerged floating tunnels (PSFTs) under horizontal and vertical earthquakes

Pier-type submerged floating tunnels (PSFTs) represent an innovative structural solution for underwater transportation, exhibiting distinct advantages and broad application prospects. To achieve a comprehensive understanding of PSFTs, evaluating the structural response of PSFTs under earthquakes is essential. This study proposes a simplified mechanical model of PSFTs considering tunnel tubes, flexible joints, bearings, and piers. The model is employed to analyse the seismic response of multispan PSFT tubes under horizontal and vertical earthquakes. A dynamic response analysis method is proposed for the seismic response calculation of PSFTs using the finite element method and the Newmark-beta method. On this basis, the modal characteristics and seismic response characteristics of PSFTs under various earthquakes are acquired. The effects of structural parameters on the seismic responses of PSFTs are further studied. The first 14 order modes are recommended for greater emphasis in dynamic analysis. The seismic response of the PSFTs is more pronounced in the horizontal direction than in the vertical direction. The vertical responses are minimal because of the suppression of the fluid inertia force. Hence, it is imperative to evaluate its responses in both the horizontal and vertical directions in seismic analysis. With respect to the structural parameters, larger span lengths contribute to increased span responses. The flexible joint stiffness substantially influences the bending moment response of the PSFTs, whereas the bearing spring stiffness considerably affects their displacement response

Fatigue damage characteristics of a flexible cylinder under concomitant excitation of time-varying axial tension and VIV

Flexible cylindrical structures are susceptible to the concomitant excitation of vortex-induced vibration (VIV) and time-varying axial tension in offshore engineering. The structural instability caused by the simultaneous excitation can lead to severe fatigue damage, threatening the safe application of cylindrical structures. In this paper, experimental research was conducted on a long flexible cylinder with an aspect ratio of L/D = 350 to investigate its fatigue characteristics under the concomitant excitation. The reduced velocity Vr ranged from 1.34 to 26.71. The axial tension excitation was characterized by three axial tension amplitude ratios Tv/Tc = 0.1-0.3 (where Tv is the tension amplitude and Tc is the constant tension) and six axial tension frequency ratios fv/f1 = 0.5-4.0 (where fv is the tension frequency and f1 is the fundamental frequency of the cylinder). The S-N curve method and the linear accumulative damage theory were employed to estimate the fatigue damage. The effects of reduced velocity, excitation amplitude and excitation frequency on the fatigue damage characteristics were discussed in terms of the fatigue damage distribution and maximum fatigue damage. The effect of the tension excitation on the fatigue damage is more pronounced at low reduced velocities (Vr <= 5.34) when the VIV is not excited, since the axial tension can excite the mode vibration. The fatigue damage area and maximum fatigue damage are significantly enhanced with the increase of the tension amplitude ratio and frequency ratio due to the occurrence of higher-order mode vibrations. The effect of axial tension excitation on the fatigue damage of the cylinder is more pronounced in the in-line (IL) direction than in the cross-flow (CF) direction. However, for a small amplitude ratio (Tv/Tc = 0.1), the tension excitation is only noticeable with a large frequency ratio (fv/f1 = 4.0). On the other hand, as the reduced velocity increases, the VIV of the cylinder is excited and dominates the fatigue characteristics. The accumulative fatigue damage distribution is aggravated with the increase of reduced velocity. The time-varying axial tension has a negligible effect on the fatigue damage distribution features and the maximum fatigue damage values of the cylinder. Nevertheless, under certain circumstances, the axial tension excitation can slightly alleviate the fatigue damage in some regions along the cylinder

深海采矿柔性管力学性能及加工工艺研究综述

海洋蕴藏着储量丰富的矿产资源，深海矿产资源开发逐渐成为学术界和工程界的研究热点。管道提升式开采方案是目前公认的最具商业前景的海洋矿产开发方案。矿产输运管道作为连接海底中继舱和海上采矿平台的纽带，需要承受恶劣的风、浪、流环境载荷和复杂作业工况的工作载荷，其设计制造和力学性能分析一直备受关注。相比于刚性管道，柔性管道的弯曲刚度小、便于安装与回收、使用寿命较长。然而，柔性管道的结构复杂，各层之间相互影响，金属柔性管道由于自身结构的限制，在深海采矿行业中难以广泛应用，人们开始把目光放在非金属柔性管的设计与应用上。本文回顾了柔性管的发展历程，总结阐述了柔性管设计及加工制造中的力学性能分析方法和力学特性，并对柔性管设计制造的未来发展提供力所能及的展望

波流联合作用下隔水管响应及水下井口受力

为确保在波流联合作用下的系统稳定性，在实际工程设计中需要充分考虑隔水管-水下井口系统的动力响应。针对东海某典型海域的复杂环境条件，考虑隔水管与井口结构间的力学特性，建立隔水管-水下井口系统的有限元仿真模型。重点关注不同环境载荷及顶张力下的结构应力、变形和井口受力的变化，并探讨井口安装偏角对结构稳定性的影响。结果表明：在不同环境载荷下隔水管对顶张力的敏感范围存在差异，在一定范围内增大顶张力可有效提升结构稳定性；水下井口受力与井口装置安装方式有关，安装偏角导致顶张力产生的等效弯矩起主导作用

A review of research on tether type submerged floating tunnels

Submerged floating tunnels (SFTs) offer many advantages over bridges and immersed tunnels, and they are regarded as the most promising form of architecture for future transportation across bodies of water. However, an SFT has not been built because there are many critical technical difficulties in its design and construction. The tether type SFT is one of the forms with the potential for transportation applications. This paper provides a review of the progress of research on tethered SFTs and discusses the critical issues and solutions involved in their design, dynamic characteristics, safety evaluation and vibration control. Although the design and the safety evaluation of SFTs can partially refer to guidelines for floating marine structures and pipes, it is essential to establish guidelines specifically for SFTs as soon as possible. The hydrodynamic and dynamic characteristics of SFTs are usually investigated based on the segmental model, which ignores longitudinal effects. To study the complete dynamic behaviour of the SFT in the longitudinal direction, it is important to establish an overall model that considers the effects of segment joints. Tests on large scale models of SFTs under the combined effects of waves, currents and earthquakes are rare, and much is unknown about the progressive collapse and failure mechanisms of these structures. Vibration control of an SFT could be achieved by hydrodynamic methods and mechanical methods. To further improve safety, it is essential to propose an adaptive control system for the vibration control of SFTs under the combined effects of various external loads